Oxygen inhibition of photosynthesis and CO(2) evolution during photorespiration were compared in high CO(2)-grown and air-grown Chlorella pyrenoidosa, using the artificial leaf technique at pH 5.0. High CO(2) cells, in contrast to air-grown cells, exhibited a marked inhibition of photosynthesis by O(2), which appeared to be competitive and similar in magnitude to that in higher C(3) plants. Wit...

Photorespiration is the light-dependent release of CO(2) initiated by Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) during oxygenic photosynthesis. It occurs during the biochemical reactions of the photorespiratory C(2) cycle, which is an ancillary metabolic process that allows photosynthesis to occur in oxygen-containing environments. Recent research has identified the genes for ma...

The CO(2) exchange of several species of fresh water and marine algae was measured in the laboratory to determine whether photorespiration occurs in these organisms. The algae were positioned as thin layers on filter paper and the CO(2) exchange determined in an open gas exchange system. In either 21 or 1% O(2) there was little difference between (14)CO(2) and (12)CO(2) uptake. Apparent photosy...

Peroxisomes are important for recycling carbon and nitrogen that would otherwise be lost during photorespiration. The reduction of hydroxypyruvate to glycerate catalyzed by hydroxypyruvate reductase (HPR) in the peroxisomes is thought to be facilitated by the production of NADH by peroxisomal malate dehydrogenase (PMDH). PMDH, which is encoded by two genes in Arabidopsis (Arabidopsis thaliana),...

BACKGROUND Recent studies using transcript and metabolite profiles of wild-type and gene deletion mutants revealed that photorespiratory pathways are essential for the growth of Synechocystis sp. PCC 6803 under atmospheric conditions. Pool size changes of primary metabolites, such as glycine and glycolate, indicated a link to photorespiration. METHODOLOGY/PRINCIPAL FINDINGS The (13)C labellin...

The cytoplasmic male sterile II (CMSII) mutant lacking complex I of the mitochondrial electron transport chain has a lower photosynthetic activity but exhibits higher rates of excess electron transport than the wild type (WT) when grown at high light intensity. In order to examine the cause of the lower photosynthetic activity and to determine whether excess electrons are consumed by photorespi...

BACKGROUND Microalgae are potential sources of biofuels and high-value compounds. Mixotrophic conditions usually promote growth of microalgae. The pennate diatom Phaeodactylum tricornutum, with its short life cycle, completely sequenced genome, and ease of transformation, can be used as a model for studying carbon metabolism in microalgae. RESULTS We compared the growth rate of P. tricornutum...